Purification of liquids by biological means



May 14, '1940. M. PRUsS Er AL 2,200,580

PURIFICATION 0F LIQUIDS BY BIOLOGICAL MEANS Filed Feb. 12, 1938 'reunited May 14, 1940 vUNITE!) STATES PATENT oFFicE PURmcA'rloN or 2152s ny BIOLOGICAL Max Prss and Heinrich Blunk, Essen-Ruhr, Germany Application February 12, 1938, Serial No. 190,290

In Germany December 24, 1934 2 Claims.

This invention relates to the purification by bacteriological treatment of watery liquid, such for example as industrial trade wastes and sewage and this application isa continuation, in part, of applicants prior application, Serial No. 54,957, filed December 1'1, 1935.

It is well known to treat sewage by means of an open bacteriological filter, in which the impure water is caused to trickle down through a mass of broken stone or other supporting media providing a number of interstices, to which air under atmospheric pressure is admitted. As the consequence there forms on lthe support afllm of aerobic' micro-organisms which retain and consume the organic matter in the impure water, and thereby destroy it. However, a very serious defect of that kind of bacteriological filter is that it gives off stench and provides a breeding ground for 4multitudes of flies. It` has also been found that present filters are much less eicient than they might be owing to insufficient oxygen reaching the bacteriological lm and consequent failure to maintain, in a healthy condition, all the micro-organisms that the lter is capable of accommodating. A

It has previously been proposed to mitigate the nuisances mentioned and -to increase the eiliciency of the filter by coveringlin the filter and providing a closed circuit by means oi which air is continuously circulated through the filter in the opposite direction to that of the water to be treated: a sufliciency of fresh air being admitted to the circuit andthe air discharged from the circuit being chemically de-odorized.

It is the object of the present invention to provide a process and apparatus whereby the stench.

and fly nuisances are definitely avoided and the emciency of the bacteriological treatment is considerably improved. l

According to the present invention, in a process for the bacteriological treatment of organically impurified watery liquid comprising the trickling of-the impure liquid downward through a bacterially active contact mass in which an oxygen-containing gas such as air is present, the process is conducted Within an enclosure; the gas is forced through the contact mass under controlled pressure and volume so as to b e calculated to reach all parts of the contact mass: the gas flow is downward through the mass; and separation of the gas from the liquid is effected below the mass where the liquid has been purified, whereby contamination of the separating air by contact with untreated water is avoided. lNo very high pressure of the air or other gas -is re- -rings or the like.

(Cl. 21o-7) quired, it having been found for. example in one plant where the invention has been applied, that a pressure ofl 2 water gauge above the filter bed gives very much more satisfactory results nthan a 10" watergaugesuction working against the resistance of the depth of the filter.

The process will be further described with reference to the apparatus-shown schematically in the accompanying drawing.

Referring to the accompanying drawing which is a vertical cross section of a suitable percolating 1ter,"a is closed container having near the bottom a perforated plate, screen or gridb on which the filling material or packing c rests, which may consist of broken stone, porcelain The water to be purified is pumped from a tankg, by means of `pump I, tol the sprayingnozzle hl The air or. other oxygen-containing gas for the purpose of'maintaim ing bacteriological activity, is blown in by a suitable fan m by pipe d, and is forced downwards through the filling material Ain close contact with and in the same direction as the :water to be purified, which is sprayed on to the filling material from the nozzle h. The air or gas being positively fed to the apparatus, its volume and rate of supply canl be regulated' so as to ensure that it penetrates to all parts of the contact mas's, and thus maintains the later in' a high state of activity. 'Ihe air or gas issues from the pipe e, purified, havingy separated from the liquid at the bottom of the filter, where the liquid itself is purified and the air'or gas then passes away by the discharge pipe e without being contaminated by coming into contact with incoming impure liquid. A screen or the like means may be used to remove from the gaseous products flowing through the pipe e any flies which may have escaped alive from the filter. The purified liquid passes out through the pipe i into settling 'tank l. where it deposits -the oxydised matter, and dead organisms, which are removed from the bottom of tank I whenever required. The clarified ef-.

fluent overflows the lip of the tank l and is run off by pipe n.

other oxygen-containing gas, by the pipe d or by another channel if more convenient, and the passage of the sulphuretted hydrogen through the filter renders it; inodorous and the gaseous mixture leaving the apparatus by the pipe e is quite inoffensive. The stench given off by the liquid distributed over the top of the iilter fouls the air that is being forced into the chamber, but the air in spite of being rendered malodorous in this way is rendered innocuous by passing.

biological filter bed, forcing the liquid into said closed spacedistributing said liquid over said lter bed, forcing an oxygen-containing gas into said space under superatmospherc pressure whereby the liquid, said oxygen-containing gas, and any malodorous gases given off by said llq uid travel confluently downwardly through said filter bed, and the liquid and said malodorous gases are simultaneously purified in said bed, and separating the puried liquid and the gases below said bed.

2. The process as defined in claim l in which hydrogen sulphide is delivered under superatmospheric pressure to said closed space in addition to the liquid to be purified and the oxygencontaining gas, thereby preventing the growth of moulds, algae, and the like on the filter bed.

MAX PRSS. HEINRICH BLUNK. 

